RE: VFA Artifacts on X+Y Straight Edges
Since I don't know the reason they used a smooth pulley in that location I can't really knock it, but I'll try this to see if it makes any difference.
https://ellis3dp.com/Print-Tuning-Guide/articles/troubleshooting/vfas.html
RE: VFA Artifacts on X+Y Straight Edges
Considering that several people seem to have gotten machines crooked due to shipping mishandling could that be measured maybe to be sure its actually square?
RE: VFA Artifacts on X+Y Straight Edges
Measuring between 39.9mm and 40.1mm at the extremes. So square enough!
I just recalibrated the IS with an accelerometer and then reprinted the squares. The frequencies and chosen algorithms changed but output squares in a blind test are identical to prior.
Same results of vertical lines on each side of varying intensity.
Pretty obvious to me that it's a mechanical issue.
RE: VFA Artifacts on X+Y Straight Edges
Measuring between 39.9mm and 40.1mm at the extremes. So square enough!
I just recalibrated the IS with an accelerometer and then reprinted the squares. The frequencies and chosen algorithms changed but output squares in a blind test are identical to prior.
Same results of vertical lines on each side of varying intensity.
Pretty obvious to me that it's a mechanical issue.
Have you checked that the belts run in the correct plane everywhere, relative to the idlers and motor gears? Belt teeth brushing against the rim of a wheel have been mentioned as the culprit in various places (for other printer models). I assume you have long since checked this, but did not see it mentioned.
RE: VFA Artifacts on X+Y Straight Edges
As much as I can without removing the belt and motor. Not much is particularly visible without disassembling the carriage which I don't want to do without support.
RE: VFA Artifacts on X+Y Straight Edges
Prusa support, after some chasing on live-chat have decided to put it in for priority repair - I will have to box it up and send it back!
I've documented enough in this thread to debug it! Printed at least a spool of filament in test prints to get good photos for Prusa to debug.
RE: VFA Artifacts on X+Y Straight Edges
Glad to learn that they are taking this seriously. I hope you will get a perfectly working printer back very soon! And I hope you will still be told what was wrong with it and can share it here.
The need to return the printer must be more than a solitary mishap. One of the few how-to pages specific for the Core One describes how to package it for repair or return shipping: https://help.prusa3d.com/guide/packing-the-prusa-core-one-for-return-original-packing-material_829350
I hope that by the time I receive my kit Prusa will have figured out a few of the teething issues, so the instructions can point out what to watch out for -- or component quality control can be tightened in the right spots.
RE: VFA Artifacts on X+Y Straight Edges
Here is someone with the Bambu having the same problem.
RE: VFA Artifacts on X+Y Straight Edges
I had commented on that video 2 years ago. I had forgotten I had watched it. In my comment I had suggested changing the smooth idler with a toothed one. Same thing I'm doing to my XL. Kinda funny I guess, again because I had completely forgot about that
RE: VFA Artifacts on X+Y Straight Edges
To add some doubt to the mix, here is a string connected CoreXY printer (no toothed belts!) showing the same artefacts - so the toothed pulley cannot be a factor.
https://forum.duet3d.com/topic/4246/vertical-banding/33
It looks like the issues stemmed from stepper motors & driving currents in this case
RE: VFA Artifacts on X+Y Straight Edges
More motor issues 🙂
RE: VFA Artifacts on X+Y Straight Edges
To add some doubt to the mix, here is a string connected CoreXY printer (no toothed belts!) showing the same artefacts - so the toothed pulley cannot be a factor.
https://forum.duet3d.com/topic/4246/vertical-banding/33
It looks like the issues stemmed from stepper motors & driving currents in this case
You could be right. In other threads some users said it helped and others not, and I myself am not 100% confident it will fix the issue. That being said in the video Bamboo responded that it was caused by resonance in the belt from the belt traveling over the pulleys, so the thought of changing to a toothed pulley might help has merit. If it doesn't help at least I'll know it's not the cause in my case.
RE: VFA Artifacts on X+Y Straight Edges
Things I have seen first-hand cause those (or very similar) artifacts on my other 3 printers (Mk3S+, Voron 0.2, QIDI Q1 Pro):
- non-toothed idlers (or cheap, non-Gates idlers)
- badly misaligned idlers (possibly due to cheap bearings)
- dual-gear extruders (particularly with the smaller hob gears like the Bondtech ones in the Mk3S+ and others)
- not having microsteps enabled on the motors
- borderline over/under driven motor current settings
And apparently phase stepping and related calibration (or lack thereof) is an issue as well. I look forward to more people getting Core Ones and helping figure out the true root causes and workarounds for same.
RE:
Seems like a dial test indicator would be handy for diagnosing these sorts of problems. A cheap one would do just fine, since you'd only really care about relative concentricity rather than absolute measurements. Something like this[1] for like $20 (there are a bunch on amazon as well). Also get an indicator holder with a magnetic base. It's really useful to have some metrology kit on hand, even if it's cheap.
RE: VFA Artifacts on X+Y Straight Edges
I got my Core One today and I can report my machine has no issue with VFA's at all. I am very sensitive to this issue because my MK4 suffered from it and I tried a lot to fix it, so I am very happy that my Core One does not have this issue.
I tried to print the outer wall at 45, 120 and 200mm/s and there are no VFA's at any of those speeds. The MK4 I had before was the worst at 45-80mm/s and disappeared at around 120-180mm/s.
I am really curious why some machines have it and some don't.
RE:
I wouldn't be surprised if this turns out to simply be a motor problem in most cases, rather than an idler pulley issue. It would be nice, if true, because it would suggest that all happy Mk4(s) owners won't have to be concerned about this problem following conversion because their motors have already been proven to work properly.
-J
RE: VFA Artifacts on X+Y Straight Edges
If I were to send you some gcode, do you mind printing in a glossy filament for me just to check? It is most apparent on a shiny pla blend
I wouldn't be surprised if this turns out to simply be a motor problem in most cases, rather than an idler pulley issue. It would be nice, if true, because it would suggest that all happy Mk4(s) owners won't have to be concerned about this problem following conversion because their motors have already been proven to work properly.
-J
RE: VFA Artifacts on X+Y Straight Edges
I wouldn't be surprised if this turns out to simply be a motor problem in most cases, rather than an idler pulley issue.
But wouldn't the 2 mm period be a strange coincidence then? The period of a motor revolution is much longer, the period of a single step much shorter.
RE:
Sorry I meant Boris would you be willing to print a gcode for me in a shiny filament and post pictures for comparison?
I got my Core One today and I can report my machine has no issue with VFA's at all. I am very sensitive to this issue because my MK4 suffered from it and I tried a lot to fix it, so I am very happy that my Core One does not have this issue.
I tried to print the outer wall at 45, 120 and 200mm/s and there are no VFA's at any of those speeds. The MK4 I had before was the worst at 45-80mm/s and disappeared at around 120-180mm/s.
I am really curious why some machines have it and some don't.
RE: VFA Artifacts on X+Y Straight Edges
Sure, is PLA fine?
Sorry I meant Boris would you be willing to print a gcode for me in a shiny filament and post pictures for comparison?
I got my Core One today and I can report my machine has no issue with VFA's at all. I am very sensitive to this issue because my MK4 suffered from it and I tried a lot to fix it, so I am very happy that my Core One does not have this issue.
I tried to print the outer wall at 45, 120 and 200mm/s and there are no VFA's at any of those speeds. The MK4 I had before was the worst at 45-80mm/s and disappeared at around 120-180mm/s.
I am really curious why some machines have it and some don't.